Federal Treasurer Wayne Swan has admitted the government made mistakes with its plan to crack down on employee share schemes.

Unions and business have joined forces to criticise the budget policy under which anyone earning more than $60,000 would have to pay tax on their employee scheme shares up front rather than when they're sold.

The government acknowledged the income cap was "maybe too low", Mr Swan said.

"I certainly think mistakes have been made," he told ABC Radio, adding critics of the measures had made "some sensible" points.

But Mr Swan would not indicate by how much the income threshold should be raised, saying a decision would be made after consultation with interest groups.

"I'm not going to buy into the income level," he said, adding the government was committed to stopping the schemes being rorted by people on higher incomes.

AAP